Vertex AI's FunctionCall/FunctionResponse protos have no id field; emitting it made Vertex reject tool calls with 400 'Unknown name id'. The id is now stripped only when the routed provider is vertex/vertex-partner (threaded via credentials._provider), preserving it for the public Gemini API where Gemini 3+ uses it for signature matching.
Co-authored-by: nullbytef0x <nullbytef0x@users.noreply.github.com>
